Oropharyngeal dysphagia is a difficulty in swallowing, which arises from abnormalities of muscles, nerves or structures of the oral cavity, pharynx, and upper esophageal sphincter. Some patients have limited awareness of their dysphagia, and exhibit or complain of no symptoms, and in these cases the dysphagia may go undiagnosed and untreated. Such patients are at a high risk of pulmonary aspiration, and aspiration pneumonia secondary to food or liquids going the wrong way into the lungs. Patients presenting with “silent aspiration” do not cough or show outward signs of aspiration.
Tracheotomy is a surgical incision directly into the anterior aspect of the trachea for the purpose of establishing an artificial airway. A tube is placed into the surgically created opening to maintain the airway, resulting in what is usually referred to as a tracheostomy. Patients in hospital or long-term care settings are often intubated with a tracheal tube in order to assist in breathing, and patients with tracheostomies frequently have dysphagia or other swallowing problems. The resulting association between aspiration and tracheostomy has been well documented. (S. K. Epstein, Respiratory Care 2005, 50:542-549.) Due to the risk of aspiration pleumonia, is of critical importance for treating clinicians to identify and evaluate such problems.
At present, the fiberoptic endoscopic examination of the swallow (FEES) and the modified Evans blue dye test (MEBDT) are the standard examinations used by clinicians to detect swallowing disorders. MEBDT is much faster and simpler to perform, and detects about 85% of cases without the clinician having to resort to FEES. In administering the MEBDT, a clinician, such as a Speech and Language Pathologist, will dye a patient's food (e.g. applesauce) with a blue dye, deflate the cuff within the tracheal tube and then feed the dyed food to the patient. Subsequently, the clinician suctions the tracheal tube to collect fluids from the lower region of the tracheal tube. If the patient has dysphagia, then some of the dyed food will have entered the trachea and traveled to the region past the deflated cuff, so that when suctioning is performed, some of the dyed food will be present in the collected fluids. The presence of a swallowing disorder is confirmed upon identifying blue dye in the suctioned fluids.
The MEBDT has only moderate sensitivity and a poor negative predictive value, and it results in many missed diagnoses of swallowing disorders. (A. Fiorelli et al., J. Cardiothoracic Vasc. Anesth. 2016, 51053-0770:30295-6.) Moreover, the technique relies on several poorly controlled variables, including the duration of suctioning, the technique of the operator, and other factors which render MEBDT highly subjective. Moreover, the test relies on feeding foods to patients who potentially have a swallowing disorder, which may put patients at unnecessary risk, and is inapplicable where a patient is comatose or otherwise unable to cooperate.
There is therefore a need in the art for an improved method of evaluating swallowing disorders that is safer, more accurate and is less invasive to a patient, and requires little or no patient cooperation.